The present invention relates to an apparatus for measuring a configuration of each of a pair of lens frames of a spectacle framework in a three-dimensional manner, and to an apparatus for measuring a configuration of an article such as, for example, a demonstration lens, a spectacle lens, a template, an optical lens or the like.
An apparatus for measuring a configuration of each of a pair of lens frames of a spectacle framework is known, which comprises a holding device for fixedly holding the lens frames. As shown in FIG. 25 of the accompanying drawings, the conventional holding device comprises a pair of first and second holding members 1 and 2. The first and second holding members 1 and 2 are so arranged that at least one of the first and second holding members is capable of being translated toward and away from the other holding member in a direction indicated by an arrow 9. The at least one holding member can fixedly be retained at the translated position. The arrangement is such that, when the at least one holding member is translated toward the other holding member, opposed abutment faces of the respective holding members cooperate with each other to clamp the pair of lens frames 4a and 4a of the spectacle framework 3 horizontally. Thus, the pair of lens frames 4a and 4b are held by the holding device fixedly, but lightly or gently.
However, the conventional holding device has the following problems. That is, generally, there may be a case where, due to manufacturing errors or deformation after manufacturing, the left- and right-hand lens frames 4a and 4b of the spectacle framework 3 differ in configuration from each other, or the width B.sub.L of the left-hand lens frame 4a differs from that B.sub.R of the right-hand lens frame 4b such, for example, that B.sub.R is smaller than B.sub.L. For this reason, as shown in FIG. 25, when the pair of lens frames 4a and 4b are clamped between the first and second holding members 1 and 2, a slight gap s is left between the first holding member 1 and the left-hand lens frame 4b, so that the spectacle framework 3 cannot be held in a stable manner. Under the circumstances, if a measuring element such as a contact roller or a measuring probe disclosed in, for example, Japanese Patent Provisional Publication No. SHO 62-169009 is in contact with the inner periphery of the lens frame 4b such that the measuring element and the lens frame 4b are moved relatively to each other in order to measure the configuration of the lens frame 4b, the latter is unsteady, making it impossible to accurately measure the configuration of the inner periphery of the lens frame 4b. Further, the unsteadiness often causes the measuring element to be disengaged from the lens frame 4b so that the measurement per se is made impossible.
By the way, each lens frame of the spectacle framework has a contour which is, for example, substantially circular, rectangular, elliptic or the like in order to enable a spectacle lens to be fitted in the lens frame. Further, when the pair of lens frames are viewed vertically in a state in which the spectacles are put on his face, the pair of lens frames are arranged in a curved plane in conformity with the configuration of his face. Accordingly, in order to obtain accurate configuration information of the spectacle lens frames, it is required to know the curved configuration of the lens frames at the time the lens frames are viewed vertically, and what positions both the lens frames are arranged respectively in the curved plane, in addition to the two-dimensional configuration of each lens frame at the time the spectacle framework is viewed at front ways. In order to realize these requirements, a three-dimensional measuring apparatus has already been developed as disclosed in, for example, Japanese Patent Provisional Publication No. SHO 62-169008 and the aforesaid Japanese Patent Provisional Publication No. SHO 62-169009.
However, the above three-dimensional measuring apparatus has the following problems. That is, each of the radial displacement and the vertical displacement of the measuring element with respect to the lens frame is detected as an angle of the angular movement of the measuring element about a signal point on the outside of the lens frame. For this reason, variation in the angle with respect to the actual radial or vertical displacement is extremely small, making it difficult to accurately measure the configuration of the lens frame. Further, the variation in the angle is detected by the use of a rotary encoder. However, the detection of the variation in the angle can utilize only a part of the measuring range, that is, one revolution of the rotary encoder. Accordingly, if it is desired to raise the resolution power of the measurement, the rotary encoder is increased in size.
Apart from the above, when lenses are processed in conformity with the pair of lens frames of the spectacle framework, methods of obtaining information on numerical control processing of the lenses include a method of measuring a configuration of an outer periphery of a flat template identical in configuration with the lens frame, and a method of measuring a configuration of a lens fitting groove in an inner periphery of the lens frame, as disclosed in the aforementioned Japanese Patent Provisional Publication Nos. SHO 62-169008 and SHO 62-169009.
However, the above measuring methods have the following problem. Specifically, if the desirable lens frames are made of elongated wire material formed of metal, synthetic resinous material or the like so that there is no lens fitting groove in the inner periphery of the lens frame, or if there is no flat template, it is no longer possible for the above conventional measuring methods to obtain the information on the numerical control processing.